TOI-858 B b: A hot Jupiter on a polar orbit in a loose binary

J. Hagelberg, L. D. Nielsen, O. Attia, V. Bourrier, L. Pearce, J. Venturini, J. N. Winn, F. Bouchy, L. G. Bouma, C. Briceño, K. A. Collins, A. B. Davis, J. D. Eastman, P. Evans, B. Falk, N. Grieves, N. M. Guerrero, C. Hellier, M. I. Jones, D. W. LathamN. Law, A. W. Mann, M. Marmier, G. Ottoni, D. J. Radford, N. Restori, A. Rudat, L. Dos Santos, S. Seager, K. Stassun, C. Stockdale, S. Udry, S. Wang, C. Ziegler

Research output: Contribution to journalArticlepeer-review

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We report the discovery of a hot Jupiter on a 3.28-day orbit around a 1.08 Ma G0 star that is the secondary component in a loose binary system. Based on follow-up radial velocity observations of TOI-858 B with CORALIE on the Swiss 1.2 m telescope and CHIRON on the 1.5 m telescope at the Cerro Tololo Inter-American Observatory (CTIO), we measured the planet mass to be 1.10a0.07+0.08 MJ. Two transits were further observed with CORALIE to determine the alignment of TOI-858 B b with respect to its host star. Analysis of the Rossiter-McLaughlin signal from the planet shows that the sky-projected obliquity is λ = 99.3a3.7+3.8 . Numerical simulations show that the neighbour star TOI-858 A is too distant to have trapped the planet in a Kozai- Lidov resonance, suggesting a different dynamical evolution or a primordial origin to explain this misalignment. The 1.15 Ma primary F9 star of the system (TYC 8501-01597-1, at ρ ~11) was also observed with CORALIE in order to provide upper limits for the presence of aplanetary companion orbiting that star.

Original languageEnglish (US)
Article numberA70
JournalAstronomy and Astrophysics
StatePublished - Nov 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Binaries: visual
  • Planets and satellites: detection
  • Planets and satellites: dynamical evolution and stability
  • Planets and satellites: individual: TOI-858A
  • Planets and satellites: individual: TOI-858B


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